Exhaust manifolds for internal combustion engines may be exposed to high thermal loads. Exhaust manifolds that are integrated into cylinder heads may experience particularly high thermal loading due to the heat transfer characteristics of the integrated design. Thermal loading of an integrated exhaust manifold and neighboring components can be reduced by incorporating cooling jackets into the cylinder head. The cooling jackets can reduce the thermal stresses on the cylinder head caused by heat generated during engine operation. For example, a cylinder head having an integrated exhaust manifold is disclosed in U.S. Pat. No. 7,367,294. An upper and a lower cooling jacket encompass a major portion of the cylinder head to remove heat from the cylinder head.
However, the inventors herein have recognized issues with the above described approach. For example, the upper and lower cooling jackets may not provide uniform cooling to the cylinder head. Additionally, the flange at the outlet of the exhaust manifold may experience higher temperatures than other portions of the cylinder head because of flow patterns of the exhaust gasses within the manifold. And, the upper and lower cooling jackets of the prior approach appear to provide limited cooling of the flange area. Furthermore, the cooling jacket of the prior approach may not provide a sufficient amount of cooling to reduce the possibility of thermal degradation on a turbocharger or components positioned downstream of the exhaust manifold. Additionally, the cooling jackets may not provide enough cooling to promote catalyst function in an emission control system positioned downstream of the exhaust manifold.
As such, various example systems and approaches are described herein. In one example a cylinder head with an integrated exhaust manifold is provided, the integrated exhaust manifold including an exhaust manifold flange. The cylinder head including a coolant inlet in communication with a cylinder head cooling system higher pressure passage, a coolant outlet in communication with a cylinder head cooling system lower pressure passage, and an exhaust flange coolant passage at least partially traversing the exhaust manifold flange and in communication with the coolant inlet and the coolant outlet.
In this way, the temperature of the flange may be reduced via the flange cooling subsystem so as to decrease thermal stresses on the cylinder head. The flange cooling subsystem can decrease the likelihood of thermal degradation of the cylinder head and downstream components, such as a turbocharger, emission control system, etc. Thus, performance of the engine, turbocharger, and emission control system can be improved when the cylinder head described above is utilized.
This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that solve any or all disadvantages noted in any part of this disclosure.